A push button switch 1 of this type, as illustrated in FIG. 1 and discussed for example in published international patent application WO 2006/1065554, includes a support structure 2, or casing, of insulating material, having a generally box-like shape and defining an internal space for housing and supporting the electro-mechanical components of the switch. The support structure 2 has an opening 3, through which the internal space is connected to the outside of the support structure 2.
The push button switch 1 moreover includes an actuation mechanism 4, having a push button 5, which may be coupled with the support structure 2 for closing its opening 3. The actuation mechanism 4 also includes a coupling arrangement 6 for coupling the push button 5 to the support structure 2 in order to allow a relative guided sliding movement of push button 5 with respect to support structure 2. The sliding is required for controlling, by push button 5, an electrical switching of switch 21, which is performed, in practice, by rotating an oscillating switching member 10, for establishing/interrupting electrical connections by interacting with fixed electrical contact elements housed in the box-like structure 2, not shown in FIG. 1. In particular, the actuation mechanism 4 includes a pressure transmission arrangement 7, a rotating block 8 and a spring loaded pin 9 adapted to cooperate with the oscillating switching member 10.
The push button 5 includes a front portion provided by a key 11, and the switch 1 includes a key cover 12 which may be associated with the key 11.
In order to avoid possible jamming of push button 5 in the box-like structure 2, which is likely in particular when the push button 5 is for example subject to a manually exerted pressing force in a position which is distinct from a generally central portion of push button 5, in the above international patent application WO 2006/106554, a solution has been proposed, in which the coupling arrangement 6 is provided, which are disposed between the push button 5 and the box-like structure 2, comprising a retaining and guiding frame 6 for push button 5, which may be fixed to the support structure 2, by two small hooks 13, and which may be interposed between the push button 5 and the support structure 2.
The applicant, based on field tests, has observed that in particular when tolerances between the push button 5 and retaining and guiding frame 6 are relatively small, for example, but not exclusively, as described in the international patent application WO 2006/106554, wherein the push button 5 and frame 6 form a directly assembled cinematic system, a undesirable intrusion of dust or sand particles and construction materials and similar may occur in the sliding areas defined between the push button 5 and retaining and guiding frame 6.
Such undesirable intrusion may in some case inhibit the sliding of push button 5 with respect to the retaining and guiding frame 6, therefore causing the actuation mechanism 4 to jam.
An object of the exemplary embodiments and/or exemplary methods of the present invention is to provide a switch with a push button actuation system, which is such as to solve the above problem with reference to the switches of the known art.
This object is achieved by a push button switch, as generally defined herein. Exemplary and advantageous embodiments of the present invention are also further defined herein.
The exemplary embodiments and/or exemplary methods of the present invention may be better understood from the following detailed description of a particular illustrative and therefore non-limiting embodiment, with reference to the appended drawings. In the drawings, same or like elements are indicated by the same reference numerals.